Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.

Patents

  1. Advanced Patent Search
Publication numberUS6106223 A
Publication typeGrant
Application numberUS 09/199,178
Publication dateAug 22, 2000
Filing dateNov 24, 1998
Priority dateNov 27, 1997
Fee statusPaid
Also published asDE69821453D1, DE69821453T2, EP0919726A1, EP0919726B1
Publication number09199178, 199178, US 6106223 A, US 6106223A, US-A-6106223, US6106223 A, US6106223A
InventorsDavid Rhodri Leyshon
Original AssigneeThe Boc Group Plc
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Multistage vacuum pump with interstage inlet
US 6106223 A
Abstract
A vacuum pump comprising a plurality of vacuum stages and having a first pump inlet through which gas can pass through all the pump stages and a second inlet through which gas can enter the pump at an interstage location and pass only through subsequent stages of the pump, wherein the pump stages prior to the interstage are sized differently to these stages subsequent to the interstages such that the pump overall suits the pressure requirements and pumping capacity of the different systems attached to the first and second inlet, respectively.
Images(1)
Previous page
Next page
Claims(3)
What is claimed is:
1. A turbo-molecular vacuum pump comprising a plurality of vacuum stages and having a first pump inlet through which gas can pass through all the pump stages and a second inlet through which gas can enter the pump at an interstage location and pass only through subsequent stages of the pump, wherein the tip diameter of the rotor is smaller in diameter in the stages before said interstate location than after said interstate location, and the pump stages prior to the interstage are sized differently from the stages subsequent to the interstate and a system requiring a lower pressure is attached to said first inlet and a system requiring a higher pressure is attached to said second inlet.
2. A vacuum pump according to claim 1 having at least three turbo-molecular stages both before and after the interstage.
3. A vacuum pump according to claim 1 in which a Holweck stage is employed between the final turbo-molecular stage and the pump outlet.
Description
TECHNICAL FIELD

This invention relates to improved vacuum pumps with particular reference to those employing a turbo-molecular mode of operation.

BACKGROUND

A conventional turbo-molecular stage arrangement of a vacuum pump comprises a stack of alternate rotors and stators. Each stage effectively comprises a solid disc with a plurality of blades depending (nominally) radially therefrom; the blades are evenly spaced around the circumference of the disc and angled "about" radial lines out of the plane of the disc in the direction of rotation of the rotor stage.

The rotor and stator blades have positive and negative gradients respectively when viewed from the side in a radial line from the disc. This arrangement has the effect in molecular flow conditions of causing the movement of molecules through the pump.

There are a number of types of apparatus where a plurality of chambers needs to be evacuated down to different levels of vacuum. For example, in well known types of mass spectrometer that part of the apparatus known as the detector commonly has to be operated at, say 10-6 mbar whereas that part known as the analyser has to be operated at a different level of vacuum, say 10-3 mbar.

In addition and importantly, the throughput of gas from the different parts of the apparatus will generally vary also. For example in a typical mass spectrometer of the type discussed above, there may need to be a 60 l/second capacity for the detector and a 200 l/second capacity for the analyser.

In apparatus of the type including but not restricted to mass spectrometers, a number of different vacuum pumps are normally employed. For example, in mass spectrometers, the detector and analyser may be evacuated by separate turbo-molecular vacuum pumps which themselves need to be backed by separate pumps, for example rotary vane pumps.

There is an ever increasing need to rationalise the use of the various vacuum pumps for overall reduced apparatus size and power requirements. A single backing pump is relatively common for supporting two (or more) turbo-molecular pumps. In addition, it has more recently been proposed to employ a single turbo-molecular pump to replace two (or more) individual pumps with the single pump having a normal inlet for gas required to pass through all the stages of the pump and an intermediate inlet, i.e. between the stages, for gas required to pass through only the latter stages of the pump.

However, even these proposals for rationalisation of the apparatus pumping system do not overcome all the problems associated with size and power consumption in particular.

There is therefore a need for improved vacuum pumps in which rationalisation can be further enhanced.

SUMMARY OF THE INVENTION

In accordance with the invention, there is provided a vacuum pump comprising a plurality of vacuum stages and having a first pump inlet through which gas can pass through all the pump stages and a second inlet through which gas can enter the pump at an interstage location and pass only through subsequent stages of the pump, wherein the pump stages prior to the interstage are sized differently to those stages subsequent to the interstage such that the pump overall suits the pressure requirement/pumping capacity of the different systems attended to the first and second inlets respectively.

The invention has advantageous application to turbo-molecular pumps in particular.

In terms of suiting the pressure requirements of the different systems, that system requiring the lower pressure (higher vacuum) will generally need to be attached to the first inlet so that gas being evacuated is subject to all the stages of the pump whereas that system requiring the higher pressure (lower vacuum) will generally need to be attached to the second inlet so that gas being evacuated is subject only to the pump stage subsequent to the interstage.

In those cases, for example, in which the system needing the lower pressure (high vacuum) requires a smaller pumping capacity in terms, in particular, of speed and compression and, for example, in which the system needing the higher pressure requires a higher pumping capacity, the stages prior to the interstage can be of a smaller size than those stages subsequent to the interstage.

In the case of a turbo-molecular pump in particular, this means that the tip diameter of the rotor is smaller in the stages before the interstage than after the interstage.

In the case of turbo-molecular pumps in particular, it is preferred that there are three, four, five, six or more stages (rotor/stator pairs) both before and after the pump interstage.

In preferred embodiments associated with a turbo-molecular pump, one or more Holweck pump stages are employed between the final turbo-molecular stage and the pump outlet.

BRIEF DESCRIPTION OF THE DRAWING

For a better understanding of the invention, reference will now be made to the accompanying drawing which shows a vertical sectional view through a vacuum pump of the invention employing a turbo-molecular mode of operation and also including final Holweck stages.

DETAILED DESCRIPTION OF THE INVENTION

With reference to the drawing, there is shown a vacuum pump having a multi-component body 1 within which is mounted a shaft 2. Rotation of the shaft 2 is effected by means of a motor generally indicated at 3 positioned about the shaft 2. The position of the shaft 2 is controlled by bearings at its base generally indicated at 4 and at its top generally indicated at 5, all of design well known in the art.

The pump possesses two sets of turbo-molecular stages generally indicated at 6 and 7 before and after an interstage therebetween, respectively.

The first set of turbo-molecular stages comprises four rotors (impellers) of angled blade construction as described above and of known construction, one of which is indicated at 8 and four corresponding stators again of angled blade construction and again as described above and of known construction, one of which is indicated at 9 in the drawing.

The tip diameter D1 of the rotors is indicated in the drawing.

An inlet 10 to the first set of stages allows gas entry through a perforated inlet screen 11 in to the four rotor/stator stages of the first set.

A second set of turbo-molecular stages 7 comprises a further six rotors (impellers) of angled blade construction, one of which is indicated at 12 and six corresponding stators again of angled blade construction, one of which is indicated at 13 in the drawing.

The tip diameter D2 of these rotors is also indicated in the drawing.

At an interstage position between the first and second sets of turbo-molecular stages is positioned a stator bridge 14 of heavily perforated design.

Gas exiting from the first set 6 of turbo-molecular stages can pass through the interstage area and into the second set 7 of turbo-molecular stages.

A second inlet 16 is formed in the pump body 1 and allows entry of gas directly in to the interstage area via the apertures in the stator bridge 14.

At the exit of the second set 7 of turbo-molecular stages is a number of Holweck stages. These Holweck stages comprise two rotating cylinders 17, 18 and corresponding annular stators 19, 20 having helical channels formed therein (on one side for stator 19, on both sides for stator 20) all in a general manner known per se.

Gas exiting the Holweck stage is urged into a passageway 21 found in the pump body 1 and thence to a pump outlet 22.

In this embodiment, the sets of turbo-molecular pump stages are therefore sized to reflect the pressure requirements and pumping capacities of the respective vacuum systems to be attached to the inlet 1 and to the inlet 2 thereby leading to overall pump improvements in terms of lower power consumption and smaller size.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US5445502 *Jul 6, 1994Aug 29, 1995Matsushita Electric Industrial Co., Ltd.Vacuum pump having parallel kinetic pump inlet section
US5501583 *Nov 21, 1994Mar 26, 1996Hitachi, Ltd.Turbo vacuum pump
US5707213 *Feb 6, 1996Jan 13, 1998Balzers-Pfeiffer GmbhMolecular vacuum pump with a gas-cooled rotor
JP40323319B * Title not available
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US6435811 *Sep 11, 1998Aug 20, 2002Leybold Vakuum GmbhFriction vacuum pump with a stator and a rotor
US6461123 *Oct 24, 2000Oct 8, 2002Pfeiffer Vacuum GmbhTurbomolecular pump
US6503050 *Dec 18, 2000Jan 7, 2003Applied Materials Inc.Turbo-molecular pump having enhanced pumping capacity
US6524060 *Feb 23, 2001Feb 25, 2003Pfeiffer Vacuum GmbhGas friction pump
US6540475 *May 14, 2001Apr 1, 2003Pfeiffer Vacuum GmbhGas friction pump
US6638010 *Nov 13, 2001Oct 28, 2003Pfeiffer Vacuum GmbhGas friction pump
US6672827 *Oct 30, 2001Jan 6, 2004Seiko Instruments Inc.Vacuum pump
US6755611 *May 16, 2000Jun 29, 2004Boc Edwards Japan LimitedVacuum pump
US6824357 *Aug 27, 2002Nov 30, 2004Pfeiffer Vacuum GmbhTurbomolecular pump
US7140833Nov 4, 2004Nov 28, 2006The Boc Group, LlcIntegrated turbo/drag/regenerative pump with counter-rotating turbo blades
US7156922 *Sep 28, 2002Jan 2, 2007Leybold Vakuum GmbhMulti-chamber installation for treating objects under vacuum, method for evacuating said installation and evacuation system therefor
US7866940 *Sep 23, 2004Jan 11, 2011Edwards LimitedVacuum pump
US8105013 *Jan 9, 2006Jan 31, 2012Edwards LimitedVacuum pump
US8393854 *Sep 23, 2004Mar 12, 2013Edwards LimitedVacuum pump
US8672607 *Dec 13, 2010Mar 18, 2014Edwards LimitedVacuum pump
US8727708 *Mar 14, 2011May 20, 2014Tokyo Electron LimitedReflecting device, communicating pipe, exhausting pump, exhaust system, method for cleaning the system, storage medium storing program for implementing the method, substrate processing apparatus, and particle capturing component
US8740588 *Jan 21, 2010Jun 3, 2014Edwards LimitedMultiple inlet vacuum pumps
US8926266Feb 23, 2010Jan 6, 2015Oerlikon Leybold Vacuum GmbhMulti-inlet vacuum pump
US20030044270 *Aug 27, 2002Mar 6, 2003Jorg StanzelTurbomolecular pump
US20050000436 *Sep 28, 2002Jan 6, 2005Peter MullerMulti-chamber installation for treating objects under vacuum, method for evacuating said installation and evacuation system therefor
US20060093473 *Nov 4, 2004May 4, 2006The Boc Group, Inc.Integrated turbo/drag/regenerative pump with counter-rotating turbo blades
US20060099094 *Dec 9, 2003May 11, 2006Schofield Nigel PVacuum pumping arrangement and method of operating same
US20070031263 *Sep 23, 2004Feb 8, 2007Stones Ian DVacuum pump
US20070116555 *Sep 23, 2004May 24, 2007Stones Ian DVacuum pump
US20080145205 *Jan 9, 2006Jun 19, 2008Ian David StonesVacuum Pump
US20110135506 *May 5, 2009Jun 9, 2011Oberlikon Leybold Vacuum GmbhMulti-stage vacuum pump
US20110162678 *Mar 14, 2011Jul 7, 2011Tokyo Electron LimitedReflecting device, communicating pipe, exhausting pump, exhaust system, method for cleaning the system, storage medium storing program for implementing the method, substrate processing apparatus, and particle capturing component
US20110200423 *Dec 13, 2010Aug 18, 2011Ian David StonesVacuum pump
US20110286864 *Jan 21, 2010Nov 24, 2011Edwards LimitedMultiple inlet vacuum pumps
US20130230384 *Jul 28, 2011Sep 5, 2013Edwards Japan LimitedSplinter shield for vacuum pump, and vacuum pump with the splinter shield
Classifications
U.S. Classification415/90, 415/116, 417/250, 417/423.4, 415/143, 417/423.9
International ClassificationF04D19/04
Cooperative ClassificationF04D19/04
European ClassificationF04D19/04
Legal Events
DateCodeEventDescription
Jan 26, 1999ASAssignment
Owner name: BOC GROUP PLC, THE, ENGLAND
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:LEYSHON, DAVID RHODRI;REEL/FRAME:009712/0334
Effective date: 19990105
Feb 23, 2004FPAYFee payment
Year of fee payment: 4
Nov 9, 2007ASAssignment
Owner name: EDWARDS LIMITED, UNITED KINGDOM
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:THE BOC GROUP PLC;BOC LIMITED;REEL/FRAME:020083/0897
Effective date: 20070531
Owner name: EDWARDS LIMITED,UNITED KINGDOM
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:THE BOC GROUP PLC;BOC LIMITED;REEL/FRAME:020083/0897
Effective date: 20070531
Feb 22, 2008FPAYFee payment
Year of fee payment: 8
Mar 3, 2008REMIMaintenance fee reminder mailed
Feb 22, 2012FPAYFee payment
Year of fee payment: 12